I've been running my game with no gnomes for a while now. The basic switch is easy, I just used night elf models and saved them as gnome male and female. The hard part comes when you modify the skins to look nice. I just used excel and listed all the night elf skin files in one column and the gnome in the other and matched them up to see which files would need to be copied. The last part is the hats...each race has its own head gear for certain items. Gnomes had GNF and GNM at the end of the name and Night Elves had NEF and NEM, once I copied these over the conversion was complete...NO GNOMES !

Here's the batch I created for female conversion for the basic skins...Put all night elf and all gnome files in the same directory ( too long to list, I'll shorten to show example)